One dead, one captured. This sums up the fate of the Boston Marathon bombers. But an important question remains: were the Tsarnaev brothers terrorists? If we use the traditional definition of terrorism as an act of political violence directed against civilian targets, the answer is far from straightforward. By itself, the killing of civilians does not necessarily distinguish the Marathon bombings from recent mass killings in America’s school campuses, movie theaters, or strip malls. To classify these events as terrorism, we must ask what political ends they thought could be served by killing civilians in the United States.

Observers have sought the answer to this puzzle in the ‘Chechen connection.’ We know that the Tsarnaev family settled in the US as refugees from Russia’s war-torn North Caucasus region. We also know that the FBI had investigated the older brother in 2011 on a tip from a foreign government – likely Russia – based on information that he was a follower of radical Islam with ties to Chechen extremists. The FBI reportedly conducted a background check and interviewed Tamerlan Tsarnaev, finding no evidence of a terrorism threat. Yet even if the FBI got it wrong, the ‘Chechen connection’ implies one of two possible motivations: nationalism and religion. Neither explanation seems terribly compelling.

The least likely scenario is that the Marathon bombings were acts of nationalist terrorism by Chechen separatists. Most nationalist-motivated terror does not happen so far beyond a perceived national homeland: a Chechen nationalist bombs targets in Russia, not Boston. It is not clear how killing American civilians would serve the goal of Chechen independence, or how any change in US policy would make such an outcome more likely. US criticism of brutal Russian counterinsurgency practices in the 1990s and early 2000s caused some mild irritation in the Kremlin, but no change in strategy. Today, Moscow’s bargaining leverage is incomparably greater, with a pro-Russian strongman in Chechnya and a much-diminished rebellion.

The second possibility is that the Marathon bombings were acts of terrorism against western targets by transnational Islamist extremists. In the last decade, the Chechen insurgency has evolved from a largely secular secessionist movement to one in which Salafi-Jihadist ideology plays a far more prominent role. In a study of over 30,000 incidents of political violence in the Caucasus since 2000, we have found that attacks by Islamist groups are more likely to engage targets outside of Chechnya, tend to closely mirror international trends in suicide terrorism, and have proven more difficult to deter and suppress through counterinsurgency and policing. Yet we also found Islamist violence by Caucasus militants to be relatively infrequent. Attacks by groups associated with Doku Umarov’s Caucasus Emirate, its network of jamaats and earlier Salafi-Jihadist outfits account for some 17-19 percent of all insurgent violence in the region. Attacks by Islamic ‘moral vigilantes’ against gambling parlours, strip clubs, bars, liquour stores and similar ‘forbidden’ establishments are even more rare, at just 3 percent. The Caucasus’s status as a breeding ground for Islamist extremists is certainly real, but also quite overblown.

More importantly, little in what we know of the Tsarnaev brothers’ background supports a Wahhabist or fundamentalist bend. We know that the younger brother, Dzhokhar, lived in Cambridge, attended the public high school, where he was on the wrestling team and won a scholarship from the city to further his education after high school. His peers have described him as a “stoner” with a tendency to attend college social events uninvited. From his Russian social networking webpage (vKontakte), he describes his worldview as Islam and his personal priorities as career and money. He speaks English, Russian and Chechen, listed in that order and lists membership in two websites dedicated to Chechnya. Yet he rarely, if ever, discussed politics with his friends and acquaintances. Little that we know is consistent with the profile of a radicalized Muslim, Islamist or jihadist.

Dzhokhar’s brother’s background seems to indicate more of a commitment to both Islam and Chechen nationalism. But here too, we find little that suggests a Wahhabist with global ambitions. As far as we can tell from his online presence, Tamerlan Tsarnaev’s variant of Islam and jihadism appears to have been home-grown and self-styled, directed narrowly against the pro-Russian Chechen government rather than the west. His personal statements and selection of videos on YouTube – if the user account is indeed his – include one clip attacking the current leader of Chechnya, Ramzan Kadyrov, as an apostate, and another criticizing Kuwaiti and Saudi clerics for meeting with Chechen political and religious leaders. Other postings are more innocuous. Tamerlan’s playlist includes a music video from a renowned Chechen singer, Timur Mutsuraev – something the Taliban, for instance, would never countenance – and an instructional video for Muslims who do not speak Arabic and are unsure of how to perform a valid Salah. These postings, at most, indicate a man devoted to Islam and critical of the Chechen government, neither of which is surprising for a political refugee from the Caucasus.

Although nationalism and religion may well have played into the mix of motivations, neither seems sufficient or even satisfying as an explanation for last week’s events. A third possibility is that politics are of secondary importance in this story – an ex-post rationalization for a more idiosyncratic case of violence. What emerges instead is a rather common and sad image of mass murder perpetrators; an image which has little to do with religion or national origin or “terrorism.”

The explanation for such violence sooner lies in individual and cultural pathologies: disaffection, alienation and brotherly respect, compounded by identity crises common to second-generation immigrants. If we consider their relative ages, and what was going on in Chechnya while each was in his formative years, we can assume that the older Tamerlan was more aware of the violence in the Caucasus than Dzhokar, making him more sensitive to injustices, feeding further into a sense of “loser” status – to take his uncle’s description. Although the family eventually made it to the United States, the parents returned to the region and divorced while the brothers remained.

Dzhokar seemed to have adapted to American life better than Tamerlan. Dzhokar became a naturalized citizen; Tamerlan received only his green card. In a 2010 article for Boston University’s The Comment magazine Tamerlan declared, “I don’t have a single American friend. I don’t understand them.” His competitive boxing career ended and he dropped out of college.

This is when the radicalization is thought to have occurred in Tamerlan, who in turn seemed to have persuaded his relatively well-adjusted younger brother to go along. How he managed to do so remains a mystery. One possibility may lie in the patriarchal power dynamics of Chechen families. Given the seven-year age difference between the brothers, and their father’s absence for most of their young adult lives, Tamerlan may have emerged as the elder in their immediate family, and a father figure to Dzhokhar. Another possibility is that the opportunity to moonlight as a self-styled jihadist offered Dzhokhar a path to salvage his own increasingly tenuous ties to an ancestral homeland as well as cope with a struggling college career (after an impressive high school one). Whatever the reason, both brothers came to see the targeting of innocents as a way to overcome their own, their family’s, and perhaps their nation’s troubles.

Yet even if a specific political or religious agenda compounded the brothers’ difficult refugee upbringing and recent string of personal failures, they never articulated this agenda in a coherent way. Unlike Norway’s Anders Breivik or the US’s own Timothy McVeigh – much less Chechen and other terrorists in Russia – the brothers do not seem to have left behind a written manifesto or a statement of demands or objectives. The Boston Marathon bombings, at present, sooner resemble an expressive act of violence by alienated individuals rather than the work of an organized Islamist insurgency.

In both the Newtown Connecticut school and Aurora Colorado theatre shootings we have already seen two heinous assaults by “regular” Americans (young males and loners) whose motivations went like this: “everyone thinks I’m a loser, well I’ll show them!” No amount of alienation and social isolation is exculpatory, of course. If they are responsible for last Monday’s bombings, the brothers are mass murderers. Whether they are terrorists is less clear.